The present invention relates to a method for operating a navigation device. The navigation device thereby generically comprises an input device into which operating commands and/or location data, especially start data and/or destination data, can be entered. The input device can thereby be designed as a conventional type of keyboard or as a touch screen. By means of the input device, the user is capable of entering the data required for calculating a route that guides the user from a starting point to a destination.
Besides, the navigation device comprises a road network database. This road network database encompasses all of the necessary geographical data required for performing a routing operation when the planned route is calculated.
By means of a route calculation unit comprised by the navigation device, suitable algorithms for calculating and storing the planned route can be executed. When the route is calculated, the user data entered into the input device for specifying the desired traveling route (location data) and the data from the road network database are thereby taken into account.
In addition, the navigation device comprises a signal receiving unit for receiving position signals, particularly GPS signals. By means of an evaluation of said position signals in a position determining unit, the navigation device is capable of determining the current position of a vehicle.
Moreover, the navigation device comprises a display device, e. g. an LCD (liquid crystal display) flat screen. On the display device, in particular maps and the conventional route guidance action can be displayed.
Known navigation systems are equipped with a function referred to as map representation for displaying the route guidance action. In said map representation, the current position of the vehicle, the surrounding road network, special destinations and the planned route calculated by the navigation device are displayed. In the event that the route results to be somewhat longer than in the regular case, the size of the map representation needs to be correspondingly scaled down, so that the entire route can be displayed on the display device. However, scaling down the size of the map representation is thereby afflicted with the drawback that many details, in particular road names of roads to be traveled along the route or points where certain driving maneuvers have to be executed, cannot be represented whatsoever or else only in an insufficiently scaled-up fashion. In order to remedy this deficiency, known navigation devices are equipped with the optional function of performing a zoom into the map representation. Any such scaled-up representation of the map is thereby, however, afflicted with the drawback that the entire route cannot be represented on the display device at the same time anymore. Due to this prejudicial aspect, the user is required to manipulate the map section respectively represented on the display device along the planned route. Manipulating the map section in this way, however, comes along with the disadvantage that the driver may accidentally stray away from the planned route, resulting in that the driver will lose his/her bearings.